Question

A 1.25 kW heater works on a 220 B mains supply. What current rating would a suitable fuse have?
(a) 2 A
(b) 5 A
(c) 10 A
(d) 13 A

Answer 1

Answer:

Given, P = 1.25 kw, 1250 w V = 220v

P = VI, I = P/V, I = 1250/220

= 5.68

Hence current rating = (c) 5 A

Answer 2

The suitable fuse will have (c) 10 A.

Explanation:

It is known that Power, $P=V \times I.$

The drawn current is, $I=\frac{P}{V}.$

$I=\frac{1250}{220}(1250 W=1.25 k W)=5.68 A.$

• So, there will be a current rating of 10 A in the suitable fuse.
• There will be melting of the fuse wire, when the current exceeds 10 A.
• NOTE: The use of the fuse is protecting the power supplies like AC grid, DC power supply, etc.